Protection switching technology has been mainly applied to synchronous digital hierarchy (SDH)/synchronous optical networking (SONET) that is a synchronous optical transmission apparatus. Further, in the SDH/SONET, there is ring protection switching technology having a self-healing function such as unidirectional path switched ring (UPSR) and bidirectional line switched ring (BLSR), as well as line protection switching technology that operates in a point-to-point mode such as a 1:1 mode and a 1:N mode.
In general, the protection switching technology applied to the SDH/SONET minimizes traffic loss by completing protection switching within 50 ms, thereby preventing the communication between client apparatuses from being affected. However, in the case of a multi-protocol label switching (MPLS) label-switched path (LSP), since there is no such technology capable of performing protection switching in a physical layer, it is hard to perform the protection switching within 50 ms.
Therefore, according to conventional MPLS technology, when a failure occurs on an LSP, availability of the LSP deteriorates, so that it is not possible to ensure signal quality of traffic transmitted through the LSP. The reason is as follows. When the failure occurs, the protection switching is not rapidly performed on the LSP on which the failure occurs. The LSP should be reset, or a new route should be calculated and set in a section other than the failure section by a failure restoration function, and thus a lot of time is spent and a loss of traffic is great.
In other words, in a conventional MPLS system, the LSP is reset through a detour route by the LSP resetting and the failure restoration function, and thus a lot of time is taken for the failure restoration. Therefore, the conventional MPLS system has problems in that the availability of an MPLS network deteriorates and a quality-guaranteed service cannot be provided.